Looper carrier bearing for chainstitch sewing machines

ABSTRACT

A bearing construction is disclosed for a four-motion threadcarrying looper mechanism of a chainstitch sewing machine which requires only simple machining of the major parts of the looper mechanism to moderate dimensional tolerances and which utilizes a pair of bearing assemblies which are inserted and clamped into the mechanism and adjusted selectively for optimum axial and radial clearance.

United States Patent 1191 Ciecior Aug. 14, 1973 [54] LOQPER CARRIER BEARING FOR 1,217,929 3/1917 Fefell 1 12/200 CH S- SEWING M ACHINES 1,849,963 3/1932 Snow 308/63 X 2,884,883 5/1959 Reimer 5] Inventor: inri C fl g n 3,301,207 1/1967 Reeber et al. 112 200 Germany [73] Assignee: The Singer Company, New York, Primary Examiner-Werner H. Schroeder N.Y. Att0meyMarsha.llJ. Breen et al.

[22] Filed: Aug. 9, 1972 [211 App]. 140.; 278,907 [571 ABSTRACT A bearing construction is disclosed for a four-motion 52 us. c1. 112/200 308/63 threadflrrying mechanism fachainstitch 511 1m, (:1. 0051 1/10 Fl 6c 9/06 machine which "quires simple machining of [58] Field of Search 112/197 199 200- the Pam mechanism mderate 5 6 dimensional tolerances and which utilizes a pair of bearing assemblies which are inserted and clamped into [56] References Cited the mechanism and adjusted selectively for optimum UNITED STATES PATENTS axial and radial clearance.

921,188 5/1909 Weiss 112/200 X 3 Claims, 5 Drawing Figures LOOPER CARRIER BEARING FOR CHAINSTITCII SEWING MACHINES BACKGROUND OF THE INVENTION In chainstitch sewing machine looper carrier constructions known heretofore, journaling techniques have been used employing long cylinder bearings which were extremely difficult to adjust for axial play. It has been known to use tapered bearings of either conical or spherical shape, but these have required extremely complex machining operations to be performed on the major parts of the looper mechanism such as the looper carrier or the rock frame for the looper carrier. A disadvantage of these prior tapered bearing constructions has, therefore, been that they are difficult to adjust for wear, and replacement of a worn bearing necessitates replacement of a major part of the looper mechanism.

BRIEF SUMMARY OF THE INVENTION It is an object of this invention to provide a bearing construction for the looper carrier of a four-motion chainstitch looper in which only simple machining operations of the major parts of the looper mechanism are required and these machining operations need only be accomplished to modest dimensional tolerances, and in which wear in the bearing may be readily adjusted or bearings completely replaced without interchange of any major part of the mechanism. The objects of this invention are attained by the provision of a pair of bearing assemblies having complemental spherically shaped interengaging bearing surfaces, which bearing assemblies may be clamped into bearing accommodating apertures in the looper mechanism with provision for selective adjustment of axial and radial bearing clearances by adjustment of the degree of tightness which the bearings are clamped in place.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings of a preferred em bodiment of this invention:

FIG. 1 represents a bottom plan view of a chainstitch sewing machine having a four-motion looper mechanism to which this invention has been applied,

FIG. 2 is a longitudinal cross-sectional view taken substantially along line 2-2 of FIG. 1,

FIG. 3 is a transverse cross-sectional view of the machine of FIG. 1 taken substantially along line 3-3 of FIG. 1,

FIG. 4 is a transverse cross-sectional view taken along line 44 of FIG. I, and

FIG. 5 is an enlarged cross-sectional view taken along line 5--5 of FIG. 2.

In the accompanying drawings, 11 indicates a work supporting bed portion of a sewing machine frame in which is positioned a work supporting throat plate 12 having apertures 13 for a work feeding mechanism and an aperture 14 through which a sewing machine needle (not shown) is adapted to penetrate in the formation of stitches. Beneath the throat plate a chainstitch threadcarrying looper 15 is situated including a blade 16 which must be moved endwise across the path of needle reciprocation to seize and shed loops of thread from the needle and must also be shifted alternately sidewise to avoid the needle alternately on opposite sides thereof. The four-motion path which the looper is required to execute is well-known in the sewing machine art in machines for sewing two-thread chainstitches (Federal Stitch Type 401 As shown in FIGS. 1 and 4, a bed shaft 20 is journaled in the bed II and serves to impart the required motions to the looper. The bed shaft carries an eccentric 21 embraced by a pitman 22 which is connected by a pivot pin 23 to a rock arm 24 secured to a rock shaft 25 which is journaled in the sewing machine bed 11 for imparting the looper avoiding motion. A rock frame 26, as best shown in FIG. I, is secured by a set screw 27 to the rock shaft 25 so as to partake of the oscillatory movement of the rock shaft 25. The rock frame 26 may also be secured by a set screw 28 to a supporting pivot pin 29 also journaled in the sewing machine bed.

The rock frame 26 is formed with spaced arms 30 and 31 between which is journaled a looper carrier 35 in which looper carrier the shank 36 of the looper 15 is secured as by a set screw 37. This invention provides a novel and advantageous bearing construction between the looper carrier 35 and the rock frame 26 which bearing construction will be described in detail hereinbelow.

For imparting loop seizing and shedding motion to the looper, the looper carrier 35, as shown in FIG 5, is formed with a transverse bore 38 about which extends a cylindrical split hub 39. Embracing the hub 39 is a split clamp portion 40 of a lever arm 41 which may be locked by a clamp screw 42 in selected angular position on the cylindrical hub 39. Secured by a split clamp 43 and clamp screw 44 at the free extremity of the lever arm 41 is a ball 46. A link 48 having a spherical socket 49 embracing the ball 46 is pivotally connected by a pivot pin 50 to a pitman 51 embracing an eccentric crank pin 52 on a stud shaft 53 which is journaled in the bearings 54 in the machine bed 11. Both the stud shaft 53 and the bed shaft 20 have secured thereon sprocket wheels 55 and 56, respectively, which are connected by a timing belt 57.

By the above described separate driving trains from the bed shaft 20, the loop taker movements in mutually perpendicular directions endwise and sidewise of the looper blade are accomplished, and it will be understood that any other known driving trains may also be utilized with the bearing construction of this invention which will now be described in detail.

Referring to FIG. 5, each of the spaced arms 30 and 31 of the rock frame 26 is formed with a cylindrical bearing accommodating aperture 60. These bearing apertures 60 are axially aligned but need not be oriented or dimensioned with a high degree of accuracy. Each of the cylindrical bearing apertures 60 is transversely split and formed at each side of the split with protruding ears 62 between which a clamp bolt 63 extends.

Each of the bearing apertures 60 accommodates a bearing assembly indicated generally at 70. Each bearing assembly comprises an inner bearing element 71 formed with a central cylindrical bore 72 and an outer spherically shaped bearing surface 73. Each bearing assembly also includes an outer bearing element 74 having a cylindrical outer surface 75 dimensioned for easy accommodation in the bearing accommodating apertures 60 and an inner spherically shaped bearing surface 76 complemental to the bearing surface 73 on the inner bearing element.

The outer bearing element 74 of each bearing assembly is transversely split as at 77 so that when the clamp bolt 63 is tightened, the'outer bearing element can be deformed thereby to seek orientation and conformity with the inner bearing element so as to eliminate looseness or play" in the assembly.

Accommodated in the transverse bore 38 of the looper carrier 35 is a bolt 80 threaded as at 81 at one end and formed with an enlarged head 82 at the other end. Preferably, the bolt 80 extends beyond the looper carrier at each side and protrudes through the bearing accommodating apertures 60 in the rock frame arms 30 and 31. The central cylindrical bore 72 of the inner bearing element of each bearing assembly 70 is accommodated on the bolt 80 and preferably a nut 83 on the threaded end of the bolt is tightened to lock the inner bearing elements 71 tightly against the looper carrier at each side. For this purpose, washers 84 may be interposed between the inner bearing elements and the nut 83 and the bolt head 82, respectively.

In assembling the bearing construction of this invention, first the nut 83 is tightened to clamp the inner bearing elements against the looper carrier, and then the clamp bolts 63 are tightened until the desired clearance between the inner and outer bearing elements 71 and 74 is attained. The outer bearing element will seek proper orientation because of the spherical shape of the complemental bearing surfaces 73 and 76, thus both axial and radial clearance will be adjusted simultaneously.

Felt washers 90 may be included at each side of each bearing assembly 70 to provide lubricant dispersion to the bearings and to protect the bearing surfaces from intrusion of foreign abrasive material.

The bearing arrangement of this invention is particularly advantageous in that the machining operations required on the looper carrier 35, the rock frame 26, and the bolt 80 do not require high tolerances, yet the bearing may be quickly adjusted to remove virtually all axial and radial play from the assembly and provide an extremely stable and accurate bearing support.

Ample adjustment is provided to compensate for bearing wear so that this bearing arrangement will enjoy a long life, and when the bearing wear can no longer be compensated by adjustment of the clamp bolts 63, the bearing may be renewed simply by replacing the bearing assemblies 70.

Having set forth the nature of this invention, what is claimed herein is:

1. In a chainstitch sewing maching having a threadcarrying looper blade which is movable endwise to seize and shed needle thread loops and which is rockable sidewise alternately to avoid the path of the needle on opposite sides thereof, a looper carrier supporting said looper blade, a rock frame journalled in the machine frame for rocking motion and pivotally supporting said looper carrier on an axis transverse to the rocking axis of the rock frame such that oscillation of the looper carrier imparts loop seizing and shedding motion to the looper and rocking of such rock frame imparts needle avoiding motion to such looper, characterized by this that the bearing means pivotally supporting said looper carrier in said rock frame is carried in spaced arms on said rock frame each of said spaced arms being formed with a bearing accommodating aperture which is transversely split and provided with clamping means, a pair of bearing assemblies seated one in each of said rock frame bearing apertures, each pair of assemblies comprising an inner and an outer element formed with complemental spherically shaped interengaging surfaces, means for securing said inner elements of said pair of bearing assemblies in axial alignment relationship on opposite sides of said looper carrier, said outer elements of said bearing assemblies having exterior surfaces complemental to said rock frame bearing apertures and said outer elements being transversely split so as to be selectively deformable in response to clamping of said bearing accommodating apertures in said rock frame for simultaneously adjusting axial and radial clearance of said bearing means.

2. Bearing means for a chainstitch sewing machine looper carrier as set forth in claim 1 characterized by this that the means for securing said inner element of said pair of bearing assemblies in axial alignment relationship on opposite sides of said looper carrier comprises central bores formed in each of said inner elements of said pair of bearing assemblies, a transverse bore formed in said looper carrier, a headed bolt arranged through said bores and claiming said inner elements of said bearing assemblies securely one on each side of said looper carrier.

3. Bearing means for a chainstitch sewing machine looper carrier as set forth in claim 1 characterized by this that said rock frame bearing accommodating apertures and the exterior surfaces of said outer elements of said bearing assemblies are formed with complemental cylindrical shapes. 

1. In a chainstitch sewing maching having a thread-carrying looper blade which is movable endwise to seize and shed needle thread loops and which is rockable sidewise alternately to avoid the path of the needle on opposite sides thereof, a looper carrier supporting said looper blade, a rock frame journalled in the machine frame for rocking motion and pivotally supporting said looper carrier on an axis transverse to the rocking axis of the rock frame such that oscillation of the looper carrier imparts loop seizing and shedding motion to the looper and rocking of such rock frame imparts needle avoiding motion to such looper, characterized by this that the bearing means pivotally supporting said looper carrier in said rock frame is carried in spaced arms on said rock frame each of said spaced arms being formed with a bearing accommodating aperture which is transversely split and provided with clamping means, a pair of bearing assemblies seated one in each of said rock frame bearing apertures, each pair of assemblies comprising an inner and an outer element formed with complemental spherically shaped interengaging surfaces, means for securing said inner elements of said pair of bearing assemblies in axial alignment relationship on opposite sides of said looper carrier, said outer elements of said bearing assemblies having exterior surfaces complemental to said rock frame bearing apertures and said outer elements being transversely split so as to be selectively deformable in response to clamping of said bearing accommodating apertures in said rock frame for simultaneously adjusting axial and radial clearance of said bearing means.
 2. Bearing means for a chainstitch sewing machine looper carrier as set forth in claim 1 characterized by this that the means for securing said inner element of said pair of bearing assemblies in axial alignment relationship on opposite sides of said looper carrier comprises central bores formed in each of said inner elements of said pair of bearing assemblies, a transverse bore formed in said looper carrier, a headed bolt arranged through said bores and claiming said inner elements of said bearing assemblies securely one on each side of said loopEr carrier.
 3. Bearing means for a chainstitch sewing machine looper carrier as set forth in claim 1 characterized by this that said rock frame bearing accommodating apertures and the exterior surfaces of said outer elements of said bearing assemblies are formed with complemental cylindrical shapes. 